As has been discussed several times in the forum, any change (not just a major one) can move you back in the queue.
Even so, you should consider that we don't have official information on how the list works. Therefore, I can't guarantee that making that update will actually get you to the bottom of the list. The administrator has mentioned that the order isn't solely based on date; other factors influence it, such as the traffic you generate. However, exactly what those factors are and how they influence the ranking is a staff secret.
What I can tell you is that it doesn't matter whether you wait to be indexed or not. The moment you make a change to your project, you run the risk of being deindexed and having to wait for a new review. So, waiting to be indexed before making the update doesn't guarantee anything. For this reason, I always recommend not relying on being indexed and focusing on your users and promoting yourself.